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Ultra Sharp Diamond Sharpening Stone Set

Ultra Sharp Diamond Sharpening Stone Set

By Ultra · Knife Sharpening · Kitchen & Cooking

  • Stone size 8 x 3 in
  • Grits 300 coarse / 600 medium / 1200 extra-fine
  • 3 stones included
  • Monocrystalline diamonds electroplated onto a solid steel plate
  • Adjustable sharpening stone holder included

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Summary

A set of three 8 × 3 in monocrystalline-diamond sharpening plates (300/600/1200 grits) with an adjustable holder, for sharpening kitchen and tool knives by hand. Check the warranty in writing before you buy: the retailer advertises a lifetime guarantee, but its own policy page allows 30 days.

Strengths

  • The 8 × 3 in plates handle plane irons and wide chef knives that smaller stones don’t.
  • Diamond-on-steel plates need no soaking and no flattening, unlike waterstones.
  • Owners benchmark them against DMT and Atoma and call them good value.
  • Light pressure suffices, and cleaning is a rinse with the occasional scrub.
  • Three grits — 300, 600 and 1200 — cover profiling through finishing.

Weaknesses

  • 300 is the coarsest stone in this line; there is no 220 or 325 option for heavy reprofiling or chip repair.
  • The warranty is contested: the retailer advertises lifetime coverage but its written policy is 30 days, unused, in original packaging, with buyer-paid return shipping.
  • New stones need a break-in, and the manufacturer warns against flattening chisel or plane-blade backs with a brand-new stone.
  • No lubricant, angle guide or storage case is included.
  • The manufacturer’s site lists no company address, ownership or manufacturing location.

Verified specifications

ModelD38CFE — three stones plus the adjustable holder; UPC 850007323370.
Stone size8 × 3 in per stone; the manufacturer does not publish a thickness.
Grits300 coarse, 600 medium, 1200 extra-fine.
Abrasivemonocrystalline diamonds electroplated onto a solid steel plate.
Holderadjustable and included; the retailer says it fits stones 6 to 9 in long.
Suitable steelshigh-carbon, stainless and tool steels (A, O, D, CPM), plus ceramic knives, per the manufacturer.
Weightnot published by the manufacturer; a Home Depot product-details mirror lists 2.2 lb per stone and about 8.5 lb of total package weight.
In the boxthree stones and one holder; no lubricant, angle guide or storage case.
Powernone — hand sharpening only.
Warrantythe manufacturer states “No Questions Asked 100% Guarantee” with no duration; the retailer advertises a lifetime guarantee but its written policy is 30 days.
Full research notes and sources

Quality control signals

No instrumented professional test of this set exists — no RTINGS, Wirecutter, Tom’s Guide, CNET or PCMag review turned up. The most detailed negative review is a 2024 YouTube video with a companion blog. The reviewer paid $60 for a three-stone set the blog describes as 2 × 6 in stones, which points to the smaller 6 × 2 in variant rather than this 8 × 3 in set, so its findings may not transfer exactly. On that set, the 300 grit profiled A2 tool steel at 64 HRC well, but the 600 grit had raised plating spots visible to the naked eye that scratched bevels, and the 1200 grit had large plating clumps and grit contamination that marred the finish.

A Reddit discussion of the review references a claimed 10% failure rate, and a separate Reddit owner reported heavy grit contamination — 30 to 60 micron particles — on the Ultra Sharp 3000 grit stone, which is not part of this set. The blog’s author moved to Sharp B stones (about $70 for a 3 × 8 in 325/1200 stone) and a Koraku stone instead. The retailer says it has tested every diamond sharpening stone and that the Ultra Sharp performs as well as or better than any of them — a retailer claim, not independent testing. Treat these as signals from a small number of owners, not defect rates.

Warranty and where to buy

The warranty needs clarification before you buy. Best Sharpening Stones advertises a “No Questions Asked 100% Lifetime Guarantee” on the product page and a lifetime warranty on its category page, but its own guarantee page accepts returns only within 30 days, unused, in original packaging, with the buyer paying return shipping. The manufacturer’s site promises only a “No Questions Asked 100% Guarantee” and states no duration. A 2015 forum post described a lifetime warranty from the retailer, but no documented case of a claim honored beyond 30 days exists, so treat the written 30-day terms as the enforceable baseline. Get the terms in writing from whoever you buy from.

The manufacturer’s MSRP is $166.74 with the holder, and $143.94 for the same three stones without it (model D38CFE-NH). Best Sharpening Stones, in Tomball, Texas, is the manufacturer’s own retail destination rather than an independent third party; in October 2026 it listed the set at $128.95 with the holder and $116.95 without, with free shipping over $99. October 2026 snapshots of Home Depot listings showed the same set with holder at $61 and at $80 — the two captures disagree, so treat $61–80 as the observed range.

Maintenance and running costs

These are hand stones with no power source, so running costs are just lubricant and cleaning products. The manufacturer recommends Krud Kutter — about $8 per quart at Lowe’s and Home Depot — and says plain water or glass cleaner also work; owners report using mineral oil, mineral spirits or Krud Kutter. No lubricant is included. New stones need a break-in before use, and the manufacturer explicitly warns not to flatten chisel or plane-blade backs with a brand-new stone. Keep a puddle of lubricant on the stone, rinse periodically to remove loose diamond particles, clean with Krud Kutter and a nylon brush, and remove rust discoloration with Bar Keepers Friend; dry before storage. The diamond-on-steel construction does not need flattening, unlike waterstones. Replacement stones are sold individually: $42.95 to $48.95 each at Best Sharpening Stones and $56.34 to $58.74 each from the manufacturer. The holder alone is $17.95 at the retailer.

Is it worth it?

The differentiators are the 8 × 3 in plate size, monocrystalline diamond construction, no-flattening maintenance and the included holder — not the “10x faster” claim, which nobody has measured (the retailer says 8x). At Home Depot’s $61–80 the set undercuts the $166.74 MSRP by more than half and competes directly with DMT Dia-Sharp kits that cost more per stone. At Best Sharpening Stones’ $116.95–$128.95 it is fair if the 8 × 3 in size matters to you. At the $166.74 MSRP it is overpriced against every observed street price for the identical set. Owners benchmark against DMT: a 2015 Sawmill Creek owner found his Ultra Sharp combination stone “sharpens just as quickly as my DMT benchstone”, a 2020 BladeForums member called the diamonds “a good value”, and a Reddit owner with several Atoma plates called the Ultra Sharps “superior in my view” after about a year.

Which model this is

This page covers the Ultra Sharp Diamond Sharpening Stone Set, model D38CFE (UPC 850007323370), sold with the adjustable holder. The same three stones are sold without the holder as D38CFE-NH (UPC 850007323493).

The Amazon listing for this set is ASIN B01FPP46W2.

It is not the 6 × 2 in Ultra Sharp II line, the 2-stone 8 × 3 in sets, the DC38 300/1200 combination stone, or the D38CFE22 600/1200/2200 set — check the model number before you buy.

Sources

Manufacturer:

Independent reviews:

Owner reports:

Retailer and listings:

Buying guides for this category

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